Today, Napster does not work anymore as explained due to copyright violations reasons.
One of the most efficient file transfer protocol used today is Bittorrent. Bittorrent also divides files in blocks and allows files to be downloaded from several nodes at the same time. This provides good redundancy in case of node/link failures, but also allows an efficient utilisation of the available link bandwidth by using uncongested paths (the node with the highest bandwidth will automatically serve blocks faster than a congested node). A Bittorrent node will not necessarily receive blocks in sequence. Furthermore, to ensure that all Bittorrent users contribute to the system, Bittorrent implementations apply the tit-for-tat principle which implies that once a node has received a block, it must serve this block to other nodes before being allowed to download new blocks.
Additional information about the Bittorrent protocol may be found in
Several Distributed Hash Tables have been proposed in the literature. One of the first and most influential ones is Chord
Ion Stoica, Rober t Morris, David Karger, M. Frans Kaashoek, Hari Balakrishnan , &#x201C; Chord: A Scalable Peer-to-peer Lookup Service for Internet Applications&#x201D; ACM SIGCOMM 2001